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cgroup/cpuset: Add cpuset_can_fork() and cpuset_cancel_fork() methods

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In the case of CLONE_INTO_CGROUP, not all cpusets are ready to accept
new tasks. It is too late to check that in cpuset_fork(). So we need
to add the cpuset_can_fork() and cpuset_cancel_fork() methods to
pre-check it before we can allow attachment to a different cpuset.

We also need to set the attach_in_progress flag to alert other code
that a new task is going to be added to the cpuset.

Fixes: ef2c41cf38 ("clone3: allow spawning processes into cgroups")
Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2023-04-11 09:35:59 -04:00 committed by Tejun Heo
parent 42a11bf5c5
commit eee8785379
1 changed files with 86 additions and 11 deletions
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97
kernel/cgroup/cpuset.c
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@ -2453,6 +2453,20 @@ static int fmeter_getrate(struct fmeter *fmp)
static struct cpuset *cpuset_attach_old_cs;
/*
* Check to see if a cpuset can accept a new task
* For v1, cpus_allowed and mems_allowed can't be empty.
* For v2, effective_cpus can't be empty.
* Note that in v1, effective_cpus = cpus_allowed.
*/
static int cpuset_can_attach_check(struct cpuset *cs)
{
if (cpumask_empty(cs->effective_cpus) ||
(!is_in_v2_mode() && nodes_empty(cs->mems_allowed)))
return -ENOSPC;
return 0;
}
/* Called by cgroups to determine if a cpuset is usable; cpuset_rwsem held */
static int cpuset_can_attach(struct cgroup_taskset *tset)
{
@ -2467,16 +2481,9 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
percpu_down_write(&cpuset_rwsem);
/* allow moving tasks into an empty cpuset if on default hierarchy */
ret = -ENOSPC;
if (!is_in_v2_mode() &&
(cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
goto out_unlock;
/*
* Task cannot be moved to a cpuset with empty effective cpus.
*/
if (cpumask_empty(cs->effective_cpus))
/* Check to see if task is allowed in the cpuset */
ret = cpuset_can_attach_check(cs);
if (ret)
goto out_unlock;
cgroup_taskset_for_each(task, css, tset) {
@ -2493,7 +2500,6 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
* changes which zero cpus/mems_allowed.
*/
cs->attach_in_progress++;
ret = 0;
out_unlock:
percpu_up_write(&cpuset_rwsem);
return ret;
@ -3264,6 +3270,68 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
percpu_up_write(&cpuset_rwsem);
}
/*
* In case the child is cloned into a cpuset different from its parent,
* additional checks are done to see if the move is allowed.
*/
static int cpuset_can_fork(struct task_struct *task, struct css_set *cset)
{
struct cpuset *cs = css_cs(cset->subsys[cpuset_cgrp_id]);
bool same_cs;
int ret;
rcu_read_lock();
same_cs = (cs == task_cs(current));
rcu_read_unlock();
if (same_cs)
return 0;
lockdep_assert_held(&cgroup_mutex);
percpu_down_write(&cpuset_rwsem);
/* Check to see if task is allowed in the cpuset */
ret = cpuset_can_attach_check(cs);
if (ret)
goto out_unlock;
ret = task_can_attach(task, cs->effective_cpus);
if (ret)
goto out_unlock;
ret = security_task_setscheduler(task);
if (ret)
goto out_unlock;
/*
* Mark attach is in progress. This makes validate_change() fail
* changes which zero cpus/mems_allowed.
*/
cs->attach_in_progress++;
out_unlock:
percpu_up_write(&cpuset_rwsem);
return ret;
}
static void cpuset_cancel_fork(struct task_struct *task, struct css_set *cset)
{
struct cpuset *cs = css_cs(cset->subsys[cpuset_cgrp_id]);
bool same_cs;
rcu_read_lock();
same_cs = (cs == task_cs(current));
rcu_read_unlock();
if (same_cs)
return;
percpu_down_write(&cpuset_rwsem);
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem);
}
/*
* Make sure the new task conform to the current state of its parent,
* which could have been changed by cpuset just after it inherits the
@ -3292,6 +3360,11 @@ static void cpuset_fork(struct task_struct *task)
percpu_down_write(&cpuset_rwsem);
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
cpuset_attach_task(cs, task);
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem);
}
@ -3305,6 +3378,8 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
.attach = cpuset_attach,
.post_attach = cpuset_post_attach,
.bind = cpuset_bind,
.can_fork = cpuset_can_fork,
.cancel_fork = cpuset_cancel_fork,
.fork = cpuset_fork,
.legacy_cftypes = legacy_files,
.dfl_cftypes = dfl_files,